1. Technical Field
The invention relates generally to mobile communication devices, and more particularly to a mobile communication device, for example, a mobile phone with a digital camera module having a focusing function.
2. Description of Related Art
Currently, digital camera modules are in widespread use in a variety of portable electronic devices, such as mobile phones, notebook computers and personal digital assistants (PDAs). Most portable electronic devices are becoming progressively more miniaturized over time, and digital camera modules are correspondingly becoming smaller and smaller. Besides having a small size of a digital camera module, consumers still demand excellent imaging performance, such as focusing function.
Focusing techniques have been widely employed in various imaging systems, including, e.g., still camera systems and video camera systems. The focusing function is carried out by a mechanism wherein a distance between a lens assembly and an image sensor is varied by changing the internal spacing of two or more of the elements of the camera module along an optical axis. Generally, the camera module usually uses an actuator, such as step motor, to drive a lens assembly of the camera module to achieve the focusing function. However, the step motor is relatively bulky in volume. In addition, the step motor consumes a substantial amount of power, especially relative to the amount of power that can be stored in the typical battery system.
What is needed, therefore, is a mobile communication device with a digital camera module having a simple and energy-efficient focusing mechanism.